The present invention is directed to a closed circulation tissue warming apparatus for use during surgery to maintain the temperature of tissues at a desired level and to a method of using the apparatus in prostate surgery. The apparatus is particularly useful in cryosurgery to prevent damage to tissues surrounding a surgical site from the extremely cold temperatures employed therein. The apparatus is especially useful during transperineal cryoablation of the prostate gland in human males to maintain the temperature of the urethral tissues and thereby prevent urethral sloughing. The apparatus may also have utility where it is desired to lower the temperature of surrounding tissues, such as during laser ablation.
Temperature variation of body tissues by irrigation with or circulation of thermal fluids is known as shown by patents to Elliott, U.S. Pat. No. 2,058,780, Albright, U.S. Pat. No. 2,077,453, Antiles, et al., U.S. Pat. No. 3,125,096, Dato, U.S. Pat. No. 3,425,419, and Kurucz, U.S. Pat. No. 4,844,074. However, these prior patents do not suggest either the specific structure of the apparatus of the present invention or the advantages obtained therewith in terms of control, ease of use, uniformity of fluid flow and temperature, and utility in cryoablation surgery of the prostate.
Elliott, U.S. Pat. No. 2,058,780, discloses a thermo therapeutical method and apparatus for treatment of body cavities, such as the vagina, rectal applications for treatment of the prostate gland, and the like. In this apparatus a distensible bag of conductive material is inserted into the body cavity and water or other fluid at a moderate temperature is introduced under sufficient pressure to cause distension of the bag. The Water circulates through the bag and its temperature is gradually elevated to the level desired for effective treatment of the area. Elliott discloses the thermal application using this apparatus and method to be useful in destruction of pathogenic bacteria without destroying the tissues being treated. There is nothing to suggest such a closed circulation of fluid in conjunction with cryosurgery to prevent damage to surrounding tissues. Furthermore, the structure of Elliott's, i.e. a simple bag, does not provide a uniform flow of fluid through the system for even temperature maintenance, rather, flow through Elliott's device will tend to be turbulent. However, the present system, by employing a catheter wherein the fluid path is through concentric lumens, achieves a more uniform flow and more even temperature throughout its length. With regard to prostate treatment, the Elliott device discloses direct application of heat to the prostate using the patented device whereas the present system is principally for use in combination with cryogenic surgery of the prostate to prevent damage to the surrounding tissues of the urethra.
Albright discloses a therapeutical appliance in the form of applicators adapted for insertion into various natural body cavities for application of heat by circulating hot water through the applicator. The structure of the applicator comprises a relatively long tube of thin elastic rubber having a central integral rubber web dividing the tube into two parallel channels joined at the tip. Such a structure is not suggestive of the apparatus of the present invention which provides improved flow of the circulating fluid, a more even application of thermal treatment to tissues and simultaneous drainage of the cavity being treated through a structure comprising concentric lumens.
Antiles, et al., U.S. Pat. No. 3,125,096, presents a body cooling apparatus whereby a refrigerant can be delivered to and evaporated within the body to effect cooling thereof. The structure of the apparatus used, while comprising multiple lumens within an esophageal tube is principally that of a balloon catheter with the balloon forming the refrigeration chamber. The lumens within the esophageal tube are separate and independent and comprise refrigerant introduction and removal tubes, a pressure monitoring tube and a stomach evacuation tube and are not concentric. Furthermore, there is no suggestion of use of such a device in the urethra in the manner of the present invention.
Dato, U.S. Pat. No. 3,425,419, discloses a method of lowering and raising the temperature of the human body by use of a thermal exchange catheter inserted within the flowing blood stream of the body. The catheter employed is an elongated tubular device of stainless steel and comprises, in one form, an inner tube and a concentric outer tube which communicate at the tip. Inasmuch as this device is designed for use in the blood stream, there is no provision for drainage of the body while the device is in use. Nor is there any suggestion of use in combination with cryogenic means for controlling the temperature of tissues around a cryogenic surgery site.
Kurucz, U.S. Pat. No. 4,844,074, discloses a method and apparatus for introducing a fluid into a human or animal organism and a method and heating device for temperature control. The apparatus and method are particularly directed to use in peritoneal dialysis and relate to the introduction of a physiological fluid at a prescribed temperature where the fluid is pumped through a controlled heating device into a gravity tank from where it is delivered to the body by gravity flow through the heating device a second time. This patent is particularly directed to the structure and function of the heating means and contains no disclosure relating to control of tissue temperatures around a cryogenic surgical site. Nor is there any disclosure relating to structure of an apparatus providing a means for closed circulation of the heated fluid within a body cavity while providing for simultaneous drainage of that cavity. In fact, it is not at all evident from the patent that the Kurucz system is, or is intended to be, a closed circulation system.
Similarly, concentric lumen and balloon catheters are also known such as devices disclosed by Schossow, U.S. Pat. No. 3,087,493; Samson, et al., U.S. Pat. No. 4,571,240; Samson, et al., U.S. Pat. No. 4,597,755; Sugiyama, et al., U.S. Pat. No. 4,955,895; Markel, et al., U.S. Pat. No. 5,053,004; and Arney, et al., U.S. Pat. No. 5,047,045. However, none of them suggest the structure of the present catheter nor the advantages obtained thereby in terms of uniform flow and temperature maintenance. Furthermore, there is no suggestion of use of this type of catheter in a method of cryoablative prostate surgery.
Devices currently on the market that the inventor is aware of and which bear the closest resemblance to the apparatus described herein are a urethral dilation balloon catheter manufactured by Cook Urological and the Level 1 Fluid IR-600 Normothermic Irrigation Set manufactured by Level 1 Technology. However, these devices do not include the structure of the present device nor do they provide a closed circulation system with the attendent advantages therein.
The Cook device is limited to a balloon dilation catheter wherein a latex balloon is expanded by filling it with air for the specific purpose of dilating the urethra. No provision is made for circulation of a warming fluid in either an open system or a closed system. Neither does this device suggest the catheter structure of the present invention wherein concentric lumens allow for counter current flow of a warming fluid for even temperature maintenance along the urethra.
The Level 1 Northermic Irrigation Set does provide a means for maintaining urethral temperature. However, this is not a closed circulation system, rather it is an open irrigation system that uses warmed water to prevent hypothermia in a patient. This device employs a standard Foley catheter for delivery of warmed irrigating liquid into the patient and does not provide any means whereby that liquid may be returned to a reservoir for recirculation. In this sense it is more in the nature of a lavage system. Furthermore, fluid pressure is maintained solely by gravity flow and, therefore, cannot provide the regulation of constant and even tissue warming and the maintenance of tissue temperature that the powered system of the present invention provides.
Accordingly, the Cook and Level 1 devices neither disclose nor suggest the apparatus of the present invention and its method of use.